Automatic blind and hit detector



c. G. HIERONYMUS ET AL AUTOMATIC BLIND AND HIT DETECTOR Nov. 5, 1946.

Filed. Dec. 11, 1943 w im h 5 2 Allkll 8 SW m m T G N MMWE R VED O l T IHR.W .T .GHJ. A CG Y B Patented Nov. 5, 1946 AUTOMATIC BLIND AND HIT DETECTOR Charles G. Hieronymus, Hollis, N. Y., and Garvice H. Ridings, Summit, and Raleigh J.

Wise, Dunellen,

N. J., assignors to The Western Union Telegraph Company, New York, N. Y., a corporation of New York Application December 11, 1943, Serial No. 513,918

8 Claims.

This invention relates generally to an automatic blind and hit detector device, and more particularly to such a device for use with terminal repeater equipment employed in half-duplex telegraph printer circuits.

The present requirement of high transmission speed of telegraph messages makes necessary the'rapid detection of any interruption in the transmission of the signals, since an interruption of only a very small part of a second in transmission may cause the garbling of an important word when recorded on a telegraph printer, reperforator, or similar recording device. For this reason it is highly important that a hit or break against the transmission be prevented from passing through the telegraph repeaters and that means be provided which will cause a prompt indication or alarm to be given at the repeater stations to notify an attendant of trouble on the circuit.

Teleprinter circuits are usually operated on half-duplex circuits in which transmission may proceed in either direction over the line, although when a station which is receiving wishes to send means must be provided to transmit a long break or a series of blank characters to render the sending station inoperative and also notify the sending station that the station which is receiving wishes to send. A short interruption due to a hit on the line, however, generally does not affect the station which is transmitting, and thus the station may be unaware of its occurrence, although as above stated it is apt to cause an error in the recorded message at the station which is receiving.

In telegraph parlance, to blind a repeater is toso arrange the repeater that line signals received by it from one direction, for example, from the east, will be passed on in another direction, for example, to the west, but signals received from the west will not be passed on to the east. The principal advantage of a blinding arrangement in connection with the present invention is that when a hit on the line occurs at a pointseparated by one or more repeaters from the station then transmitting, the hit will not appear in the intermediate sections between the transmitting station and the section in which the hit occurred, and this prevents the transmitted characters from being distorted or garbled in the intermediate repeater sections or in the transmitting station or in receiving stations connectedto the intermediate repeater stations.

One of the objects of the invention is an automatic blind and break detector in which the 2 receiving side of a repeater associated therewith is automatically blinded while the transmitting side is transmitting, and in which a hit or break against the transmission is prevented from passing through the repeater.

A further object is improved indicating means for. producing a signal upon the occurrence of a hit on the line and for distinguishing between a hit and an intentional break againsttransmission. c

Another object is a device of the character described, in which a relatively long break on the line or a continuous sequence of "blank characters will cause the repeater to become unblinded and the break signal caused to pass through the repeater and break the transmission on the rest of the network.

Still another object is an automatic blind and break detector in which means are provided for readily eliminating the automatic blinding fe.a-, ture when desired without impairing the em.- ciency of the apparatus to function as a break detector. g

An additional object is an automatic blind and break detector which may readily be connected to a telegraph repeater of conventionaldesign such that the detector may be connected or disconnected at any time without interfering with the operation of the repeater.

The foregoing and otherobjects and advantages will be apparent from the following description, taken in connection with the accompanying drawing which illustrates one embodiment oi the invention as applied to a half-duplex telegraph repeater.

Referring to the drawing, various of the relays illustrated are designated by reference letters generally suggestive of their functions, viz., main line relay 7 MLR, leak relay LR, intermediate relay IR, transmitting relay TR, sending relay SR, receiving relay RR, blind relay BR and hit relay HR. The equipment shown may be located between a line section L and a line section or subscribers drop 15, and preferably comprises terminal equipment at a sending and receiving station such as a stop-start teleprinter station S or P. The relays MLR, LR, IR, TR, SR and RR are polar relays, with marking and spacing con: tacts m ands. In the circuit illustrated, the operating windings of these relays are wound in such direction that, as they are viewed in the figure, current flowing from right to left through their windings normally causes the armatures or tongues of the relays to be actuated to the marking position m, and current flowing inthe oppo-' site direction, 1. e., from left to right, through the windings causes the relay armatures to be actuated to the spacing position s. For simplicity, plus and minus symbols are employed in most instances to designate positive and negative grounded battery, respectively.

As seen in the drawing, the telegraph line L is connected to one of the operating windings H) of the main line relay MLR, the other winding H of the relay being connected through an artificial line network AL to ground; The apex of the windings I and H is connected by conductors I2 and I3 to the armature or tongue of the transmitting relay TR. The armature of the latter relay is connected by conductors l3 and 14 through a high resistance IE to the control grid l6 of the amplifier section of an electron tube I! which preferably, although not necessarily, is of the type known as No. 117L7GT. The value of the resistance IS in the embodiment illustrated is of the order of one megohm, and the potentialon the grid l 6 of tube I1 is maintained negative until transmission starts, by reason of the negative battery supplied by the marking contact m and armature of the relay TR. Conductor [2 also extends to a gaseous discharge tube 20, for example, a neon tube, which is connected to ground at 2|.

The armature or tongue of relay MLR is connected by conductor 26 to the grounded winding 2'! of intermediate'relay IR and also to the grounded winding 3| of leak relay LR. Connected to the conductor 26 is'a conductor 30 which includes a blind indicator device, such as a lamp 32, the circuit also extending to a conductor 33, Winding of hit relay HR and conductor 34 to the anode or plate 35 of the rectifier section of tube l1. Conductor 30 also extends to the middle make contact 36 and armature of the blind relay BR, and from its armature extends through the right hand blade of the automatic blinding switch SW7, when closed, toground at The spacing contact s of relay LR is connected by conductor 38 which includes resistance 39, to the screen grid 40 of the amplifier section of tube I1. The screen grid circuit is connected to a condenser 42 which is connected to ground at 43. The circuit also extends through a resistance 44 and conductor 45 to positive grounded battery 19. The battery 19 is also connected to the heater elements or filaments 46 of tube l1 and thence to ground 41. The left hand portion of conductor 45 extends through a resistance 50, winding 5| of relay IR, conductor 52, outer make contact 54 and armature of the relay BR, and through the left hand blade of switch SW, when closed, to ground at 3-1.

The spacing contact s of relay IR is connected by conductor to the winding 6! of relay TR, and thence to positive grounded battery. Armature of relay IR is connected bya conductor 64 to the marking contact m of relay SR. The grounded winding 660i relay TR is connected, through conductor 51, winding 68- of relay RR, and conductor 69, to the armature of relay SR. The left hand winding 10 of relay SR. is connected to ground at H, and the right hand winding 72 is connected to the line or subscribers drop 15. The two windings 10 and" are in opposition to each other, and the mid-point of these windings is connected by conductor 13 to the armature of relay RR. Winding 14 of relay SR is connected at one end to negative grounded battery and at its other end to ground, and operates as a biasing winding for the-relay. The winding 16 of relay RR is connected at one end to positive grounded battery, and at its other end by a, conductor 11 to the spacing contact of relay SR.

The operating winding of blinding relay BR, which is a slug relay of the slow-release type, is connected in a circuit comprising positive battery 19, resistance 80, conductor 8|, winding of the relay, and conductor 82 to the plate or anode 83 of the amplifying section of tube IT. A condenser 84 is bridged across the winding of the relay to increase its slow-release characteristic. The inner make contact and armature of the relay BR is connected in a circuit which includes ground at 31, conductor 9| and the cathode 92 of the rectifier section of tube 11.

Operation of the circuit When transmission is not taking place in either direction, a steady marking condition is maintained on the line L, and the armatures or tongues of the polar relays remain at their marking positions m, since the armature 25 of the main line relay MLR is held against its marking contact 112 at this time. Assume, however, that station S starts transmission, in which case a spacing signal is received over the line L. This causes the armature 25 of relay MLR to move to its spacing contact s, thereby applying positive grounded battery to the operating windings 3| and 21 of relays LR and IR, causing their armatures to be actuated to their spacing contact 5. The movement of the tongue of intermediate relay IR to its spacing contact applies positive grounded battery to winding 68 of receiving relay RR, through a circuit comprising the winding El of relay TR, conductor 66, spacing contact and tongue of relay IR, conductor 64, marking contact m and tongue of sending relay SR, conductor 69, winding 68 of relay RR, conductor 87 and winding 66 of relay TR to ground. This causes the armature or tongue of relay RR to move to its spacing contact 3, thereby sending a spacing or no-current signal to the' subscribers start-stop printer P on line 15. The current for operating the relay RR flows from positive battery through the windingsof relay TR in such a direction as to hold the tongue of TR against its marking contact. Since the tongue of relay TR remains against its marking contact during the reception of signals from line S, negative potential is maintained on grid 16 of tube il thereby preventing the tube from becoming conducting and inadvertently operating the break relay BR. This insures that false operation of the hit relay HR will not occur during normal transmission from station S, notwithstanding that the tongue 25 of relay MLR intermittently'engag'es its spacing contact during such period of transmission. A biasing winding 14 of relay SR holds the tongue of SR against its marking contact when thespacing signal is sent to the subscribers line, which removes battery from the other windings l0 and 12 of relay A following marking signal received from the line L causes the tongue of the main line relay MLR to return to its marking contact. This operates relays LR and IR so that their tongues move to their marking contacts. The negative battery now supplied through the tongue of relay IR operates relay RR, through its winding 68,

, causing the tongue of relay RR to move to its marking contact, thereby applying negative grounded battery to the junction of the opposed windings ii! and T2 of relay SR, and through the winding 12 of relay SR to the subscribers drop 15. The current from the tongue of relay-RR also flows through the winding Ill of relay SR to ground at H, the direction of the current flow in windiings and 12 of relay SR being such as to neutralize their magnetic effect.

When the operator or subscriber at station P is transmitting to station S, through the repeater circuit shown, the first signal received from station P will necessarily be a spacing signal which is transmitted momentarily by opening the line 15. This line being opened, current ceases to flow in winding 12 of relay SR. Winding ll! of relay SR continues to carry current, however, from the tongue and marking contact of relay RR, and this current is of suificient strength to overcome the effect of the biasing Winding M of relay SR, and cause the tongue of relay SR to move to its spacing contact. This closes a circuit through grounded winding 66 of relay TR, conductor 61, winding 68 of relay RR, conductor 69, the tongue and spacing contact of relay SR, conductor 11, and winding 16 of relay RR, to positive grounded battery, thereby operating relay TR. Relay RR does not operate, however, because the currents flowing in windings 68 and 16 are in opposition to each other. Relay TR operates to move its tongue to its spacing contact, and the spacing signal from line is through the winding 10 of the main line relay MLR to the line L. The next signal from station P that is marking in character causes negative current to flow in winding 12 of relay SR through the line 15 to ground at station P. By reason of the flow of current through winding 72, the effect of the biasing winding 14 is such as to move the tongue of relay SR from its spacing contact to its marking contact. The RR relay does not follow signals transmitted by station P, and therefore the tongue of the relay will remain on its marking contact. The circuit thus established by relay SR causes marking battery to flow through winding 68 of relay RR and winding 56 of relay TR to ground, thus operating relay TR to its marking position, and transmitting a marking signal through the winding H] of relay MLR to the line L.

The only transmission which operates relay TR is that from the subscribers line '55. The grid l6 of the tube l'l' is connected through a one megohm resistor IE to the tongue of the transmitting relay TR, and the potential on the grid is negative until transmission starts. TR relay operates, the positive potential on its spacing contact is applied to the grid of the tube, causing plate current to flow and operating the relay BR in the detector through a circuit which comprises positive battery 19, resistance 8i conductor Bl, winding of relay BR, conductor 82, anode 83 of tube H, and cathode 85 to ground. The relay BR is a slow-release relay to prevent it from following the transmitted signals, and does not release on continuous letters characters during transmission from line 15. The slow-release characteristics are obtained by a suitable slug over the core of relay BR and, as heretofore stated, this characteristic is further enhanced by the condenser 84 bridged across the operating winding of the relay.

Assuming the blinding switch SW to be closed, the outer make contact 54 and armature of operated relay BR closes a circuit from ground at 31, left hand blade of switch SW, armature and contact 54, conductor 52, winding 5| of relay IR, conductor 45 and resistance 50, to the grounded battery 19, causing current to flow through the winding 5| of relay IR in a direction tolockits armatureagainst the marking contact and prevent it As the from following any breaks on the circuit that operates main line relay MLR. The inner make contact 36 and armature of relay BR complete a circuit, when the relay is operated, from-ground at 31, right hand blade of switch SW, armature and contact 36 of the relay, and conductor 30 through a blind indicator lamp 32, the circuit continuing through conductors 3c and 26 to the armature 25 and marking contact of MLR to negative grounded battery. The lamp 32, which may be of distinctive color, for example, red, remains lighted so long as the automatic blinding switch SW is closed and the station P on line 15 is transmitting through the regenerative repeater to the line L, thereby giving a visual signal to this effect. 7 Should transmission from station P cease, the tongue of transmitting relay TR will move to its marking contact, and hence the potential on the grid N5 of tube I! will again become negative, thereby causing the deenergization of relay BR and extinguishing the lamp 32. The neon tube 20 serves as a protective device to limit the potential applied to the control grid I6 and to protect it from any surges which may occur in the circuit.

It is necessary for the screen grid 40 of tube l! to have a positive potential applied to it to allow plate current to flow through the BR relay circuit when the transmitting relay moves to its spacing contact. This required positive screen potential is applied by the condenser 42 which is held charged through a high resistance 44 from battery 19. A connection is also made from the screen grid 49 through conductor 38 and resistance 39 to the spacing contact of the leak relay LR. Since the tongue of this relay is connected to negative battery, the operation of this relay following signals received on the MLR relay will apply an opposing negative voltage to the screen grid and thus prevent operation of the BR relay while the main line relay is operated. This arrangement prevents signal lights from appearing on two repeaters (one on which the break occurs and the other on the one receiving) even if the blinding switch SW of the detector circuit is thrown to its off position.

The relay BR controls a circuit extending from the tongue of relay MLR is on its marking contact, the negative current will not flow through the coil of relay HR. A break or hit on the line L, however, causes the tongue of relay MLR to move to its spacing contact, and positive battery is applied to this circuit and causes relay HR to operate. The operation of relay HR closes an alarm circuitv comprising grounded battery I00, conductor till, operated armature and contact M2 of HR, conductor I03, winding of a signal relay lfi'd, conductor )6, through the normally closed contacts ID? of a push button I08, and thence to ground at H39. Relay I05 operates and locks up through a circuit from the battery I00, armature Hi4 and make contact of the relay, winding of the relay and through the push button contacts Hi! to ground I09, so that the relay I05 remains locked up until the push button I08 is opened by an attendant. A grounded armature H0 and make contact of the relay I05 controls.

comprise'a lamp H2 and a bell or buzzer H3; so long as relay 105 is locked up these alarm devices continue to give both visual and audible alarm signals indicating a hit, until the relay IE5 is deenergized by thedepression of push button I08.

Any hits occurring on the line L during the transmission of signals from station S to station Paredetected by a similar regenerative repeater and automatic blind and hit detector at station S, it being understood that station S includes the circuit and apparatus illustrated in connection with station P, including a sending and receiving printer. A further function of the circuit associated with the screen grid 40 of tube I! is to permit a break'by the operator at station P when transmission is being eiiected from station S to station P. When station P transmits a long open or a continuous sequence of blank characters, the transmission of these over line L will cause the leak relay LR. in a similar automatic blind and break detector at station S, which is sending, to apply sufficient negative potential to the screen grid 48 to cause the BR relay there to be released and thus pass the break through the repeater at the sending station. If the operator at station P is transmitting to line L and the other station S wishes to break the transmission, the operator at the latter station sends a long open or succession of blank characters. These characters when received by the main line relay MLR cause the tongue 25 of the relay tobe actuated and remain against the spacing contact, causing relay LR, to be operated to its spacing contact, and thus applying negative battery to the screen grid 40 so that relay BB. is released and the break is received at station P. Since the printer at station P is of the sending and receiving type, the operator at station P will note from his printed copy or from the lapse of printing operations at his printer that the station S Wishes to break. The automatic blinding feature is optional; if not desired it maybe cut out by throwing the switch SW to its off position, and the circuit will still function as a hit or break detector.

Assuming a hit or break to occur in line L while station P is transmitting, the tongue of rela MLR will move to its spacing contact as a result of the hit or open on L. Negative battery will then be applied to the tongue of MLR and through conductors 2E, 30 and 33, the winding of HR, conductor 35, the anode 35 and cathode 92 of rectifier section of tube I1, and thence to ground through conductor 9i, the make contact 90 and armature of relay BR to ground, causing relay HR to be operated and actuate alarm relay 05. Relay IR will not be operated and will not repeat the hit or open from line L to station P because the tongue of relay IR is held against its marking contact by positive grounded battery 19 which flows through resistance 30, conductor 45, winding 5! of IR, conductor 52, outer make contact 54 and armature of relay BR. through switch SW to ground 31.

Hits on lin L which occur during transmission from station P through the repeater to the line L will not cause errors to be recorded at station P in regard to the sending subscribers own transmission. This is of importance where another repeater is connected at the same station with the one shown in the drawing, andthose which at station B may be transmitting simultaneously to another'line or lines, In such case, hits on line L would not cause errors in ignals sent from Poverthese other repeaters.

Various modifications of the circuit arrangement shown, and various equivalents or substitutes for the devices illustrated, will readily occur to those versed in the art, without departing from the spirit and scope of the present invention. For example, separate tubes may be employed instead of the composite tube l1, and other known types of amplifier, relay and rectifier devices suitable for the purpose may be employed instead of those shown. The disclosure, therefore, is for the purpose of illustrating the principles of the invention which is not to be regarded as limited except as indicated by the scope of the appended claims.

What is claimed is:

1. In a half-duplex system, a telegraph line and a two-way repeater connected thereto for repeating permutation code impulses received from and transmitted to the line, said repeater comprising a line relay having an armature operable between marking and spacing contacts for producing negative and positive current pulses respectively in accordance with marking and spacing impulses received from said line, means including a relay in said repeater for transmitting permutation code impulses to said line, means operable when transmission of code impulses is proceeding tosaid line for detecting a hit on the line, said means including a hit detecting relay controlled by the armature of said line relay and operable when the armature of the line relay is actuated to its spacing contact by a hit occurring on the line for giving an indication of such condition, and relay means automatically operative to prevent false operation of the hit relay when the armature of the line relay engages its spacing contact during the normal reception of code impulses received from said line.

2. In a half-duplex system, a telegraph line and a two-way regenerative repeater connected thereto for repeating start-stop code impulses received from and transmitted to the line, said repeater comprising a line rela having an armature operable between marking and spacing contacts for producing negative and positive pulses respectively in accordance with marking and spacing impulses received from said line, means including a relay in said repeater for transmitting start-stop code impulses to said line, means operable when transmission of code impulses is proceeding to said line for detecting a hit on the line, said means including a hit detecting relay controlled by the armature of said line relay and operable when the armature of the line relay is actuated to its spacing contact by a hit occurring on the line for giving an indication of such condition, means for preventing operating current from passing through the hit relay when the armature of said line relay is against its marking contact, and relay means automatically operative to prevent false operation of the hit relay when the armature of the line relay engages its spacing contact during the normal reception of code impulses received from said line.

3. In a half-duplex system, a telegraph line and a two-way regenerative repeater connected thereto for repeating start-stop code impulses received from and transmitted to the line, said repeater comprising a line relay having an armature operable between marking and spacing contacts for producing negative and positive pulses respectively in accordance with marking and spacing impulses received from said line, means including a relay in said repeater for transmitting start-stop code impulses to said line,'means operable when transmission of code impulses is proceeding tosaid line for detecting a hit on the line, said means including a hit detecting relay controlled by the armature of said line relay and operable when the armature of the line relay is actuatedto its spacing contact by a hit occurring on the line for giving an indication of such condition, means including a rectifier for preventing operating current from passing through the hit relay when the armature of said line relay is against its marking contact, and relay means automatically operative to prevent false operation of the hit relay when the armature of the line relay engages its spacing contact during the normal reception of code impulses received from said line.

4. In a half-duplex system, a telegraph line and a two-way regenerative repeater connected thereto for repeating start-stop code impulses received from and transmitted to the line, said repeater comprising a line relay having an armature operable between marking and spacing for producing negative and positive pulses respectively in accordance with marking and spacing impulses received from said line, means including a relay in said repeater for transmitting start-stop code impulses to said line, means operable when transmission of code impulses is proceeding to said line for detecting a hit on the line, said means including a hit detecting relay in circuit with the armature of said line relay and operable when the armature of the line relay is actuated to its spacing contact by a hit occurring on the line for giving an indication of such condition, means including a rectifier connected in series with the operating winding of said hit relay for preventing operating current from passing through the hit relay when the armature of said line relay is against its marking contact, and relay means automatically operative to prevent false operation of the hit relay when the armature of the line relay engages its spacing contact during the normal reception of code impulses received from said line.

5. In a half-duplex system, a telegraph line and a two-way regenerative repeater connected thereto for repeating start-stop code impulses received from and transmitted to the line, said repeater comprising a line relay having an armature operable between marking and spacing contacts for producing current pulses respectively in accordance with marking and spacing impulses received from said line, means including a relay in said repeat-er for transmitting start-stop code impulses to said line, means operable when transmission of code impulses is proceeding from the transmitting side of the repeaterto said line for detecting a hit on the line, said means including a hit detecting relay controlled by the armature of said line relay and operable when the armature of the line relay is actuated to its spacing contact by a hit occurring on the line for giving an indication of such condition, and circuit connections including a space discharge tube and a relay controlled thereby for automatically blinding the receiving side of the repeater while the transmitting side thereof is transmitting to the line thereby to prevent hits on the line from passing through the repeater.

6. In a half-duplex system, a telegraph line and a two-way regenerative repeater connected thereto for repeating start-stop code impulses received from and transmitted to the line, said repeater comprising a line relay having an arma- I0 ture operable between marking and spacing contacts for producing current pulses respectively in accordance with marking and spacing impulses received fromsaid line, means including a relay in said repeater having an armature and marking and spacing contacts for transmitting startstop code impulses to said line, means operable when transmission of code impulses is proceeding from the transmitting side of the repeater to said line for detecting a hit on the line, said means including a hit detecting relay controlled by the armature of said line relay and operable whenrthe armature of the line relay is actuated to its spacing contact by a hit occurring on the line for giving an indication of such condition, circuit means including a space discharge tube having a control grid and a relay controlled by the tube for automatically blinding the receiving side of the repeater while the transmitting side thereof is transmitting to the line thereby to prevent hits on the line from passing through the repeater, and circuit connections for controlling the potential applied to the control grid of said tube in accordance with the position of the armature of the said transmitting relay.

7. In a half-duplex system, a telegraph line and a two-way regenerative repeater connected thereto for repeating start-stop code impulses received from and transmitted to the line, said repeater comprising a line relay having an armature operable between marking and spacing contacts for producing current pulses respectively in accordance with marking and spacing impulses received from said line, means including a relay in said repeater having an armature and marking and spacing contacts for transmitting start-stop code impulses to said line, means operable when transmission of code impulses is proceeding from the transmitting side of the repeater to said line for detecting a hit on the line, said means including a' hit detecting relay controlled by the armature of said line relay and operable when the armature of the line relay is actuated to its spacing contact by a hit occurring on the line for giving an indication of such condition, circuit means including a space discharge tube having a control grid and a slow-release relay controlled by the tube for automatically blinding the receiving side of the repeater while the transmitting side thereof is transmitting to the line thereby to prevent hits on the line from passing through the repeater, and circuit connections for controlling the potential applied to the control grid of said tube to make the tube conducting or non-conducting in accordance with the position of the armature of said transmitting relay with respect to its marking and spacing contacts.

8. In a half-duplex system, a telegraph line and a two-way regenerative repeater connected thereto for repeating start-stop code impulses received from and transmitted to the line, said repeater comprising a line relay having an armature operable between marking and spacing contacts for producing negative and positive pulses respectively in accordance with marking and spacing impulses received from said line, means including a relay in said repeater for transmitting start-stop code impulses to said line, means operable when transmission of code impulses is proceeding from the transmitting side of the repeater to said line for detecting a hit on the line, said means including a hit detecting relay controlled by the armature of said line relay and operable when the armature of the line relay is actuated to its spacing contact by a hit occurandmean including a relay controlled by said line relay for applying negative potential to said screen grid to prevent operation of the blinding relay when said. line relay is operating,

CHARLES G. I-HERONYMUS. GARVICE H. RIDINGS. RALEIGH J. WISE. 

